150
FXUS61 KRNK 270132
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
932 PM EDT Thu Sep 26 2024

.SYNOPSIS...
Rounds of scattered showers and thunderstorms will continue
across the area tonight and Friday, with  moderate to heavy
rain associated with Hurricane Helene expected. This will
greatly enhance the threat of flooding in the mountains and
foothills. Over the weekend the remnants of the tropical system
will be trapped over the Tennessee Valley with a lower
probability and coverage of showers.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 915 PM EDT Thursday...

Key Messages:

1) Significant flooding expected; do not try and drive through
water covered roads!

2) Heavy rain, landslides, small tornadoes, and very gusty
winds are expected to be a threat for much of the area tomorrow.

In the last couple of hours Helene has acquired an eye and
increased in strength to a category 4 hurricane. The storm will
make landfall along the Big Bend of FL in the next couple of
hours. Helene is moving relatively fast at 23 mph. Minimum
central pressure was 942 mb at 8 PM EDT. After landfall, Helene
will travel inland over GA and reach east central TN by 2 pm
tomorrow.

Affects of Helene are already being felt in the southern
Appalachians, as high moisture content interacts with the
higher terrain, wringing out moderate to heavy rain. A few
tropical spinups have also been noted, mainly in Caswell County,
and this threat will continue through the night and into Friday
as rainbands from Helene arrive from the south.

Repeated rounds of rain and increased forcing for ascent have
contributed to rainfall amounts so far ranging from 3 to 7
inches in the last 24 hours from the mountains westward. To the
east, amounts have been generally resulted in less than 3
inches. An additional 1 to 3 inches is expected for the lower
terrain, with 3 to 7 inches possible for parts of the Blue Ridge
and western NC mountains. A Flood Watch remains in place for the
entire area, and we have received reports of high water rescues,
flooded roads, streams and rivers increasing to bankfull and
beyond, and at least one landslide. These problems will only
get worse as the storm nears. As a reminder- do not drive across
flooded roads, you do not know how deep the water is!

Strong sustained winds of 25 to 35 mph with gusts as high as 60
mph are expected for elevated parts of the Blue Ridge, generally
above 3500 ft. A Wind Advisory is in place for most of the
remainder of the area, with speeds of 15 to 25 mph with gusts to
45 mph possible.



As of 415 PM EDT Thursday...

Key Messages:

 - Flood Watch Expanded
 - High Wind Warning Issued
 - Wind Advisory Issued

Persistent area of moderate to occasionally heavy rain, with
prolonged rates of 1 to 2 inches per hour have resulted in
flooding southwest of a line from Bluefield WV to Yadkinville
North Carolina. As expected the amount of rain needed for flash
flooding is under one inch through much of the mountains.

Rain was filling in over the foothills and piedmont. As
Hurricane Helene moves north the shield of heavier rain will
reach the southern Appalachians. The heaviest rainfall amounts
expected from this evening through Friday evening is still along
the southern Blue Ridge.

Bufkit forecast soundings showed the potential for gusts of 40
to 60 mph at the highest elevations of southwest Virginia and
northwest North Carolina overnight and into Friday morning. The
areas favored to have enhanced wind speeds with strong southeast
surface and low level wind in Tazewell to Smyth County also
have the potential for damaging wind. These areas area now
covered with a High Wind Warning.

One change to note is that although winds will diminish in the
afternoon, gusty conditions will persist longer into the
afternoon. Plus with the saturated ground trees will more easily
by blown down. Therefore the Wind Advisory has been issued to
cover a large area and until the end of the day Friday.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Hurricane Helene will quickly weaken and mostly dissipate
Friday night into Saturday.

2) Rain chances significantly decrease for Saturday, but
increase once again on Sunday.

Hurricane Helene will have mostly moved through the area by
Friday night, with only scattered showers remaining over the
region. However, the airmass will still remain tropical, with
dewpoints in the 60s to near 70, especially in the piedmont
locations. Despite this, there is increasing confidence that
PoPs will be significantly lower on Saturday, due to drier air
in the mid-levels. Even some sunshine is expected to return for
parts of Saturday afternoon as cloud cover will lessen. The
remnant low of Helene will continue to meander through the
weekend in the Ohio River Valley, with no significant weather
systems expected to pick the storm up and move it. It will then
slowly begin to drift back to the east and into the Mid-Atlantic
on Sunday, though models differ on how quickly this will occur.
Nonetheless, this track to the east will allow showers to
develop once again on Sunday.

There is moderate confidence that QPF totals for the weekend
will generally be under 0.25" for most of the RNK CWA, according
to the NBM, with isolated areas possibly seeing up to 0.50" in
the heaviest showers. High temperatures on Saturday will be in
the 70s to low 80s, due to the break in cloud cover. Sunday will
see slightly cooler temperatures, as clouds and showers move
back over the region with highs in the 70s. Nighttime lows will
be around 60 degrees both days.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 200 AM EDT Thursday...

Key Messages:

1) Scattered showers persist for the early week as the remnant
low of Helene slowly begins to move east.

2) Drier and quieter weather finally returns for the midweek.

As the remnant low of Helene moves back over our area Sunday
night and Monday, showers will remain in the forecast as the
tropical airmass remains in place. The Ensemble Situational
Awareness Table keeps precipitable water amounts around 1.5
inches through Tuesday night. Because of this, PoPs still remain
modest for both Monday and Tuesday, though there is uncertainty
in the coverage of the rainfall across the CWA. Temperatures
will be around normal, with highs in the mid 70s, with 60s for
the higher elevations. A cold front begins to approach the area
on Tuesday, though confidence remains low on the timing as
models disagree on this. Once the front passes, much drier
conditions will move into the area, with high pressure building
back in place. This will also cause temperatures to fall below
normal, with lows possibly in the 40s across most of the CWA for
Wednesday night.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
As of 930 PM EDT Thursday...

Persistent area of moderate to occasionally heavy rain, with
prolonged rates of 1 to 2 inches per hour have resulted in
flooding southwest of a line from Bluefield WV to Yadkinville
North Carolina. Ceilings will continue to vary from IFR to MVFR
until sunset then lower to IFR/LIFR across the region
overnight. Visibility will occasionally lower to MVFR in the
heavier rain. Catastrophic, life-threatening flooding is
possible overnight into Friday, especially along the southern
Appalachians. Check your destination before you fly.

Bufkit forecast soundings showed the potential for gusts of 40
to 60 mph at the highest elevations of southwest Virginia and
northwest North Carolina overnight. By 06Z gusts of 30 to 40 kts
from the east are expected at the local TAF sites.

Average confidence for wind, ceiling and visibility.

EXTENDED AVIATION OUTLOOK...

Wind speeds diminish Friday afternoon through Friday night.

Flight conditions should improve Saturday through Tuesday. A
chance of light showers will continue around the remnants of
Helene.

&&

.HYDROLOGY...
Affects of Hurricane Helene continue to be felt in the southern
Appalachians, as high moisture content interacts with the higher
terrain, wringing out moderate to heavy rain. Repeated rounds
of rain and increased forcing for ascent have contributed to
rainfall amounts so far ranging from 3 to 7 inches in the last
24 hours from the mountains westward. To the east, amounts have
been generally resulted in less than 3 inches. An additional 1
to 3 inches is expected for the lower terrain, with 3 to 8
inches possible for parts of the Blue Ridge and western NC
mountains. A Flood Watch remains in place for the entire area,
and we have received reports of high water rescues, flooded
roads, streams and rivers increasing to bankfull and beyond, and
a landslide.

River flooding is ongoing or expected to begin shortly on the
following rivers: Clinch, New, Roanoke, and Dan.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch through Friday evening for VAZ007-009>020-022>024-
     032>035-043>047-058-059.
     High Wind Warning until 8 PM EDT Friday for VAZ007-009-015.
     Wind Advisory until 8 PM EDT Friday for VAZ010>014-016>020-
     022>024-032>035-043>045-058.
NC...Flood Watch through Friday evening for NCZ001>006-018>020.
     High Wind Warning until 8 PM EDT Friday for NCZ001-018.
     Wind Advisory until 8 PM EDT Friday for NCZ002>006-019-020.
WV...Flood Watch through Friday evening for WVZ042>044-507-508.
     Wind Advisory until 8 PM EDT Friday for WVZ042>044-507-508.

&&

$$

SYNOPSIS...RCS
NEAR TERM...AMS/SH
SHORT TERM...JCB
LONG TERM...JCB/RCS
AVIATION...AMS/RCS/SH
HYDROLOGY...SH